Automatic train stop system for railroads



NOV 2, 1937. T. KITTREDGE ET AL 2,097,624

AUTOMATIC TRAIN STOP SYSTEM FOR RAILROADS Filed Feb. 17. 19:54 2Sheets-Sheet 1 THEIR ATTORNEY.

Nov; 2, 1937. T KITTREDGE ET AL 2,097,624

AUTOMTIC TRAIN STOP SYSTEM FOR RAILROADS Filed Feb. 17, 1934 2Sheets-Sheet 2 l FIGZ.

THEIR ATTORNEY.

distant relay DR, commonly o normal condition o tice;an d,-th a t asuitable form of trip stop,

Patented Nov. 2, 1937 UNITED STATES AUTOMATIC TRAIN sToP sxrsTEM'FoR`nAlLnoAps 1 Thomasinaredge, Rthe'rfqa, N.J., and Her-f bert D.

Brooks, OceansidagN. Y;,'assignors to General Railway Signal Company,Rochester,

i Application February 17, 1934, seriaiNo. 711,700 'y A' il claims. v(craieavr yThis invention relates to automatic train `stop systems orrailroads, and more particularly to the control circuits for thevtrainstop oritrip .devices on' the track-commonly employed `insuch systemson'subwaysand thelike. 1 r One. object of this invention is toV provide;an improved organization of relays and control, cir-` cuits forelectrically controlled trip stops, which will allow the clearing of thetrip upon the en- 'trancehof atrain into the associated track sectionafter a time interval determined bythe sequential operation of the homeand distant relays commonly employed, in such a way that a longer timeinterval may be obtainedwiththe number i of relays ordinarily used thanis possible .at present.

:Other objects, characteristic features, and advantageso the inventionwillbe in part apparent, and in part pointed but as the descriptionprogresses.

The accompanying drawings show in a simplified and diagrammatic manneroneembodiment of the invention as applied to one control location, Fig.l showing the parts and circuits inthe withno trains present, and Fig, 2showing the parts and' circuits when theftrain stop is in the raised orstop'position, due to the presence of a train ahead.

In the embodiment of the invention illustrated, it is assumed that thetrackway is dividedinto blocks such as A and B in the usual manner; thatsignals-of a suitable type, such as color-light signals S, arelocated atAthe entrance to each block and controlled in accordance withA the usualpracdesignated V andshown conventionally, will be located near theentrance to each block, a prede-- termined distance in advance of theinsulated joints, this trip stop being of the welleknown type comprising`electrically controlled power mechanism for moving the trip arm fromits raised or stopping position to a clear position against a spring orcounter-weight, as 38, and maintained there. `In the form illustrated,this trip stop mechanism is assumed to be operated to the clear positionby an electric moto-r M, through gearing or the like 40, and heldinfthat position by a hold-clear device W coacting with an armature 4Ion the device V. This trip stop mechanism also vincludes a circuitcontroller, arranged to open and close contacts in different positions.This circuit controller is illustrated diagrammatically as comprisingpivoted contactarms I to 5, movable through an angle of 90, and engagingarcuate segments or stationary contacts in diilerent positions of thetrip arm.

The usual track relay T, home relay HR, and used in systems of thistype, are shown diagrammatically and conventionally. The home anddistant relays are assumed to be ofthe two-element. alternating currenttype, with local and line phase windings. Such relays operate theircontacts only when both windings are energized.

`For the purpose of simplifying the drawings, the conventional symbolsBX, NX, and CX are employed `to indicate connections to a transformersupplyingicurrent tothe various circuits, it being understood thatfBXand NX indicate vterminals having positive and negative instantaneousvoltage `in relation to the terminal CX.

Fig. l illustrates ,the parts in the normal condition with notrainspresent.v The track relays T and IT of the blocksortrack sectionsA and B are both energized. The line phase Winding H of thenlinerelay HRis energized by a circuit readily traced -rom BX 55, through the frontcontact 6 oftrack relay IT, line wire front contact 3 of track relayT,.wires 9 and IQ, winding H, to CX. The` local Winding HQ of this relayis energized over theY same `line'circuit Vthrough wire II, frontcontact IZMoirelay HR, wires I3 and I4, winding HQ, to CX.

The local winding DQ of isdirectly energized; Vand the line phasewinding Dis energized over the line circuit from NX 55, through frontcontact I5 of the line relay IHR for the block B, line wire I6, frontcontact Il of track relay T, wire I8, winding D, to CX.

The train stop V is held in the clear position. bythe energization ofhold-clear W over a circuit from BX IIQ, front Contact of track relay T,wires 2I and 22, iront contact 23 of line relay wires 26 and 25, circuitcontroller contact 3 ofthe stop mechanism, closed in the clear position,Wire 26, hold-clear W, to VNX Ill).

Thus,l under normal clear conditions, with no train present, the line-relay HR and the distant relayvDR are both energized; and the trainstop V is held in the clear position.

When a train enters block A under such clear conditions, the dropping ofthe track relay T establishes a retaining circuit for holding the tripstop in the clear positon, said circuit being from BX HG, back contact2l) of track relay T, Wire the distant relay DR 2l, circuit controllercontact l closed in the clear position, wires`28 and 28, hold clear W,to NX I I.

Considering new the case where there is a train ahead in the block B, asshown in Fig. 2, the presence of thistrain drops the track relay IT,opening its front contacts 6 and 81 to de-energize the line relays HRand IHR. The opening of theiront contact I5 of the line relay IHRdeenergizes the distant relay DR. Thus, the signal S indicates stop,block overlapv characteristicof the trip stop system. Thede-energization of the line relay HR opens its front contact 23 and thusde-energizes the hold clear W, so that the trip stop V assumes itsstopping position,

there being the usual one vided it is travelling at a very low speed.This result is obtained by locating the trip stop VY a' short distancein advance of the'insulatedjoints,`

so that the train may travel a short distance, after dropping the trackrelay T, before Vencountering the trip stop, and by providing circuitsfor clearing the trip stop after a short interval of time, so that ifthe train consumes more than a predetermined time in travelling suchpredetermined distance, corresponding with a speed below the desiredspeed limit, the trip stop-will be clear by the time the train reachesit. 'Ihis time interval is measured in accordance With this invention bythe sequential operation ofthe home and distant relays.v

VAssume now that a train enters the block A- under danger traineconditions Ywith a train ahead in the block B, as shown in Fig. 2. Thedropping of the track relay T closes a circuit for energizing thedistant relay DR, which may Vbe traced from BX 55, circuit controllercontact I of the trip stop,V closed in the stop position, Wires 3i) andi3, back vcontact l2 of the line relay HR, wire 3l, back contact I1 oftrack relay T, wire I8, winding D to CX. This energization of thedistant relay DR establishes a circuit for energizing the line phaseWinding H of the home relay HR from'BX Ill), back Contact 20 of trackrelay T, Wires 2l and 32, Ycircuit controller contact of thetrip stopmechanism closed in the stop position, wire 373, front contact 34 ofrelay DR, wires 35 and l0, winding H, to CX. 'I'he local winding HQ ofthe home relay HR is directly energized through the circuit controllercontact i of the stop mechanism.

When the home relay HR is thus energized, the closing of its frontcontact I2 provides-a circuit for energizing its line phase winding Hthrough the circuit controller contact l. Also, the opening ofthe backcontact l2 of the home relay HR de-energizes the distant relay DR, whichcloses its back Contact 36, so that a circuit for the motor M of thetrain stop mechanism is established from BX HQ, through the back Contact36 of relay DR, wires 3l and 22, Vfront contact 23 of relay HR, wire 2,circuit controller contact 2 of the trip stop mechanism, Wire 39, motorM, to NX Il.

The trip stop mechanism now operates to the clear position, the circuitcontroller contacts l and 2 remaining closed' until the trip armvreaches the clear position and circuit controller contacts 3 and l areclosed, whereupon the opening of contact i de-energizes the home relayHR, the opening of contact 2 de-energizes the motor M, and the closingofcontact 4 establishes the retaining cir-cuit through the back contact2D of the track relay T to hold the trip in the clear position.

It will be noted thatA the time interval between the dropping of thetrack relay T and the movement of the tripfstop V to the clear positionis measured by time intervals required to energize distant relay DR,then energize the home relay VHR, then de-energize distant relay DR,then move the trip arm to the clear position. Inrother words, inaddition to the usual `clearing time of theV trip stop mechanism, theorganization of control circuits in accordance with this inventionrequires they sequentialpicking up of the,l distant and home relays,followed by the dropping of the `distant relay, thereby providing anadditional time interval from the same relays commonly employed.

Various adaptations, additions, and modications, may be made in theparticular construction and arrangement of parts shown and described,Without departing from the invention.

What we claim isz- 1. In an automatic stop system for railroads, incombination, an electrically controlled stop mechanism located a shortdistance beyond the entrance to a block having the usual track relay, ahome relay and a distant relay, a clearing circuit for said stopmechanism including a front contact of the home relay and a back contactof the distant relay, and circuit means controlled by said track relayfor picking up the distant relay and home relay in Succession, and thendropping the distant relay to establish said clearing circuit.

2. In an Yautomatic train stop system of the character described, a tripstop mechanism, a track relay, a home relay, and a distant relay, meanscontrolled by said track relay and effective when thetrack relay isdeenergized and the stop mechanism is in the stopping condition, to pickup the distant relay through a circuit controlled by the home relay foractuating said stop mechanism to the clear position, after a timeinterval measured by the picking up of thedistant relay and home relayin succession, and the dropping of the distant relay.

3. An automatic'train stop for railroads, com.

prising, in combination, an electrically controlled stop mechanismlocated in a block, a track relay for said block, a home relay and adistant relay for said block, and circuit means controlled by the saidrelays for clearing the stop mechanism, when the block next in advanceis occupied, a predetermined time after the track relay has been shuntedbyroccupancy of the said block, the circuit means includingan energizingcircuit for the distant relay including a back point of the home relayand a back point of the track relay, and an energizing circuit for thehome relay including a front point of the distantrelay.

4. An automatic train stop for railroads, comprising, in combination, anelectrically controlled stop mechanism located in a block, a track relayfor said block, a home relay and a distant relay for said block, andcircuit means controlled by the said relays for clearingthe stopmechanism,

when the block in advance is occupied, a predetermined time after thetrack relay has been shunted by occupancy of the said block, the circuitmeans including an energizing circuit for the distant relay including aback point of the home relay and a back point of the track relay, and anenergizing circuit for the home relay including a front point of thedistant relay, and a. control Ycircuit for the stop mechanism requiringthe distant relay down and the home relay up, to thereby insert apredetermined time interval between release of the track relay andoperation of the stop mechanism.

THOMAS KITTREDGE. HERBERT D. BROOKS.

